On April 20, 1999, Eric Harris and Dylan Klebold walked into Columbine High School and opened fire on their classmates, teachers and staff. They killed 13 people and wounded over 20 before turning the guns on themselves. In the aftermath of the tragedy, friends of the Klebold family spoke to Inside Edition about burying their son, Dylan, as well as the guilt they felt that he was behind the worst school shooting in America at that time.